Welcome to the August 2024 issue of Research Extracts. “The Extracts” is designed to keep busy practitioners and savvy consumers up to date on the latest research on diet, nutrients, botanicals, the microbiome, the environment, and lifestyle approaches to good health and wellness. Our medical team, including NDs, MDs, PhDs, RDs, an MS in clinical nutrition, an MS in biology, and an LAc, summarizes the essence of several interesting recent studies.

In this issue: (1) Mental Health Moment: Mental and physical benefits of touch therapy, (2) gender differences in the effect of protein intake on constipation, (3) nighttime carb restriction improves athletic performance, and (4) heavy metals in tampons.

Mental Health Moment: Mental and Physical Benefits of Touch Therapy

The sense of touch is one that connects us with the physical and social world and has a wide range of mental and physical health benefits across the lifespan. This meta-analysis reviewed 212 articles to assess the evidence of health effects from touch therapy and the influences of different moderators on the therapeutic effectiveness. These components were assessed in newborn, child, and adult populations.

Touch therapies provided significant improvements in newborn weight gain and cortisol regulation, especially when the physical touch came from parents rather than health-care professionals or someone unfamiliar to the newborns. 

For adults, the benefits of touch therapy included significantly reduced feelings of depression and anxiety and decreased pain symptoms. Adults had greater mental health improvements when touch therapy was from another human rather than an object. An additional difference was found between genders. Women had significantly stronger cortisol reductions after touch therapy compared to men. When comparing healthy and clinical adult cohorts, the clinical cohorts had more pronounced mental health benefits with touch therapies, indicating greater impacts in vulnerable populations – but still positive impacts regardless of health status. More frequent touch interventions provided increased mental and physical benefits, indicating a need for repeated touch interventions to improve those health outcomes at all ages.

Regardless of the age or life stage, social connectedness and physical touch create a sense of belonging and care, as seen through the evidence here of mental and physical health benefits. 

Contributed by Carly Duffy, MPH, RD

Reference

Association Between Protein Intake and Constipation Differs in Men and Women

Chronic constipation negatively impacts quality of life for more than 14 percent of adults worldwide. Among those, women and the elderly tend to be most affected by chronic constipation. Fiber intake is commonly associated with bowel regularity, but other macronutrients such as protein may also impact the incidence of constipation.

Using data from the National Health and Nutrition Examination Survey (NHANES) 2005-2010, information from 14,048 adults ages 20 and up was analyzed for associations between dietary intake of protein and incidence of constipation. Protein intake was measured using two 24-hour dietary recall interviews. Constipation was determined by stool frequency and consistency (type 1 or 2) according to the Bristol Stool Form Scale.

Among participants, constipation was reported in 10.19 percent of women and 4.89 percent of men. Overall, individuals with constipation reported a lower total dietary intake of fiber, fat, and protein. Among men with constipation, increased protein intake was associated with lower constipation risk and the turning point of protein intake was 119.42 grams per day. For women, a higher protein intake was linked to increased risk of constipation with a dietary protein turning point at 40.79 grams per day. For men and women experiencing chronic constipation, these dietary turning points may be useful for guiding individualized protein intake.

Note: Thorne’s Advanced Digestive Enzymes, Multi-Enzyme, and Betaine HCl & Pepsin formulas promote protein digestion and help maintain bowel regularity.*

Contributed by Jennifer L. Greer, ND, MEd

Reference

Nighttime Carbohydrate Restriction for Seven Days Improved Performance and Weight in Athletes

Studies suggest that periodically reducing carbohydrates enhances exercise endurance adaptations; however, long-term carbohydrate restriction could create undo stress that impedes performance.1

A two-week parallel design study examined the effect of short-term nighttime carbohydrate restriction on body composition and performance measures in 22 university student athletes.2 

Participants were randomized into two groups of 11. During the first seven days, all participants consumed their regular diet without restriction, except for alcohol and caffeine, which were prohibited. The trial continued for another seven days with the control group (5 men; 6 women; average age 21) continuing their usual diet, while the intervention group (6 men; 5 women; average age 22) was prohibited from consuming any carbohydrates after 4 p.m. 

Throughout the two-week trial, all participants ran for 60 minutes each morning before breakfast at an intensity of 65 percent of their maximum heart rate (average 154 beats/minute) tracked by heart rate monitor.

The measurements below were assessed twice – at the end of each seven-day intervention.

  • Peak oxygen consumption (VO2 peak) and work rate max using bicycle ergometer
  • Respiratory quotient (RQ) measured using an expired gas analyzer
  • Body weight, body fat percentage, and lean body mass calculated using body composition monitor 
  • Mood profile assessed using Profile of Mood States scale for adults (POMS 2) and Total Mood Disturbance Score

Nutrient intake was meticulously tracked through the trial and no statistical differences were found in total caloric or carbohydrate intake between groups, or between weeks.

Despite caloric and carbohydrate intake being the same in both groups, body weight was significantly lower in the nighttime carbohydrate-restricted group compared to control or baseline assessment after seven days. Body fat percentages were unchanged (average 19%). 

The nighttime carbohydrate restricted group also had a significantly higher VO2 peak and work rate max, and a lower RQ during exercise compared to control or baseline.

Since RQ decreased in the intervention group despite exercise intensity remaining the same, short-term nighttime carbohydrate restriction appeared to increase fat metabolism. And, since there were no differences in mood scores among participants, the study suggests that short-term restriction of carbohydrate intake at night could be a beneficial strategy to support healthy weight and exercise adaptations.

Note: Thorne offers an array of formulas to support athletic performance and promote healthy weight management. Consider Thorne’s Training Bundle, which supports cellular energy production and power output to help athletes maximize their training.* And for those seeking support for weight and body composition, Thorne’s Weight Management Bundle features a trio of supplements to promote optimal metabolism.*

Contributed by Carina Toledo, MS, MHI, CNS

References

  1. Burke LM. Fueling strategies to optimize performance: training high or training low? Scand J Med Sci Sports. 2010;20 Suppl 2:48-58. doi:10.1111/j.1600-0838.2010.01185.x
  2. Sakamoto T, Ueda SY, Nakahara H. Effects of short-term nighttime carbohydrate restriction method on exercise performance and fat metabolism. Nutrients. 2024;16(13):2138. doi:10.3390/nu16132138

Heavy Metal Contamination of Tampons

Use of disposable tampons by menstruating U.S. women ranges from 52-86 percent. Tampons have the potential of being contaminated with heavy metals from agricultural or manufacturing processes. A recent study, conducted at Columbia University, examined the metal content of 60 samples of popular disposable tampon brands, representing 24 unique product brand/absorbency profiles. Samples were manufactured in the United States, United Kingdom, and Greece. Samples included various fabrics (cotton or rayon/viscose); and encompassed both organic and non-organic products. Samples (0.2-0.3 grams) were microwave-acid digested and analyzed via mass spectrometry. Metals tested for included minerals and heavy metals: arsenic, barium, calcium, cadmium, cobalt, chromium, copper, iron, manganese, mercury, nickel, lead, selenium, strontium, vanadium, and zinc. Results were compared among characteristics including organic/inorganic, region of purchase, brand, and type of tampon.

Results: Nearly all tested metals were detected in at least one sample, including the heavy metals lead, arsenic, and cadmium. In fact, lead was found in all the samples tested. The researchers also found high concentrations of calcium and zinc compared to the other metals tested, while they found no chromium or mercury. Metal levels varied by region of purchase, organic vs. inorganic status, and name-brand vs. store-brand product. No one category was consistently lowest in all or most of the metals. For example, organic tampons were higher in arsenic, while non-organic tampons were higher in lead. It was revealed, too, that some manufacturers purposely add certain metals during manufacturing – for odor control, as antimicrobials, or for lubrication – or all three, as is the case of calcium and zinc. 

Considering tampon users could use an average of 7,400 tampons during their reproductive lifetime, they could present a significant source of heavy metal toxicity. The researchers reported that regulations regarding tampon manufacturing in the U.S., U.K, and E.U are nearly non-existent and none of them are required to test tampons for the presence of chemicals, including heavy metals.

The next step is to determine to what extent these metals are absorbed across the vaginal mucosa.

Contributed by Kathi Head, ND

Reference